One might expect functionalism to imply that personal identity is preserved through various operations on the brain, including transplantation. I argue that this is not clearly so even where the whole brain is transplanted. It is definitely not so in cases where only the cerebrum is transplanted, a conceivable kind of hemispherectomy, and even certain cases in which the brain is "gradually" replaced by an inorganic substitute. These results distinguish functionalism from other accounts taking what Eric T. Olson calls the "Psychological Approach" to personal identity, enabling it to avoid some of his objections to them